Dialysis Associations of Dialysis Modality and Infectious Mortality in Incident Dialysis Patients in Australia and New Zealand David W. Johnson, PhD, 1,2 Hannah Dent, BSc(Hons), 1,3 Carmel M. Hawley, MMedSci, 1,2 Stephen P. McDonald, PhD, 1,4 Johan B. Rosman, MD, 1,5 Fiona G. Brown, PhD, 1,6 Kym M. Bannister, MD, 1,7 and Kathryn J. Wiggins, MD 1,8 Background: The aim of the present investigation is to compare rates, types, causes, and timing of infectious death in incident peritoneal dialysis (PD) and hemodialysis (HD) patients in Australia and New Zealand. Study Design: Observational cohort study using the Australian and New Zealand Dialysis and Transplant Registry data. Setting & Participants: The study included all patients starting dialysis therapy between April 1, 1995, and December 31, 2005. Predictor: Dialysis modality. Outcomes & Measurements: Rates of and time to infectious death were compared by using Poisson regression, Kaplan-Meier, and competing risks multivariate Cox proportional hazards model analyses. Results: 21,935 patients started dialysis therapy (first treatment PD, n = 6,020; HD, n = 15,915) during the study period, and 1,163 patients (5.1%) died of infectious causes (PD, 529 patients; 7.6% versus HD, 634 patients; 4.2%). Incidence rates of infectious mortality in PD and HD patients were 2.8 and 1.7/100 patient-years, respectively (incidence rate ratio PD versus HD, 1.66; 95% confidence interval [CI], 1.47 to 1.86). After performing competing risks multivariate Cox analyses allowing for an interaction between time on study and modality because of identified nonproportionality of hazards, PD consistently was associated with increased hazard of death from infection compared with HD after 6 months of treatment (6 months hazard ratio [HR], 1.08; 95% CI, 0.76 to 1.54; 6 months to 2 years HR, 1.31; 95% CI, 1.09 to 1.59; 2 to 6 years HR, 1.51; 95% CI, 1.26 to 1.80; 6 years HR, 2.76; 95% CI, 1.76 to 4.33). This increased risk of infectious death in PD patients was largely accounted for by an increased risk of death caused by bacterial or fungal peritonitis. Limitations: Patients were not randomly assigned to their initial dialysis modality. Residual confound- ing and coding bias could not be excluded. Conclusions: Dialysis modality selection significantly influences risks, types, causes, and timing of fatal infections experienced by patients with end-stage kidney disease in Australia and New Zealand. Am J Kidney Dis 53:290-297. © 2009 by the National Kidney Foundation, Inc. INDEX WORDS: Bacteremia; continuous ambulatory peritoneal dialysis; hemodialysis; peritoneal dialysis; peritonitis; pneumonia; septicemia; bacterial infection; fungal infection; incidence; prevalence; treatment modality; viral infection. I nfection is a major cause of morbidity and the second leading cause of death in dialysis populations. 1,2 The most common types of fatal infections recorded in dialysis registries are sep- ticemia, peritonitis, pneumonia, wound infec- tions, and urosepsis. 1,3 Some studies have ob- served greater rates of septicemia, 4 endocarditis, 5 and pneumonia 1 in patients treated with hemodi- alysis (HD) compared with peritoneal dialysis (PD). However, other studies have not ob- From the 1 Australia and New Zealand Dialysis and Trans- plant Registry, Adelaide; 2 Department of Renal Medicine, University of Queensland at Princess Alexandra Hospital, Brisbane; 3 Discipline of Public Health, University of Ad- elaide; 4 Department of Nephrology and Transplantation Services, University of Adelaide at the Queen Elizabeth Hospital, Adelaide, Australia; 5 Renal Department, Middle- more Hospital, Otahuhu, Auckland, New Zealand; 6 Depart- ment of Nephrology, Monash Medical Center, Clayton, Victo- ria; 7 Department of Nephrology, Royal Adelaide Hospital, Adelaide; and 8 University of Melbourne Department of Ne- phrology, St Vincent’s Hospital, Fitzroy, Victoria, Australia. Received February 25, 2008. Accepted in revised form July 7, 2008. Originally published online as doi: 10.1053/j.ajkd.2008.06.032 on September 22, 2008. Address correspondence to David W. Johnson, PhD, Department of Nephrology, Level 2, ARTS Bldg, Princess Alexandra Hospital, Ipswich Rd, Woolloongabba, Bris- bane Qld 4102, Australia. E-mail: david_johnson@health. qld.gov.au © 2009 by the National Kidney Foundation, Inc. 0272-6386/09/5302-0013$36.00/0 doi:10.1053/j.ajkd.2008.06.032 American Journal of Kidney Diseases, Vol 53, No 2 (February), 2009: pp 290-297 290